Insulin pump systems allow patients to administer safe doses of an intravenous or subcutaneous medication at will, without the need for constant supervision by medical staff. These devices often include a housing that houses a cartridge, a motor, a drive system, and a power supply, such as a battery, which supplies power to the motor. The outside of the housing provides key pad entry for allowing the patient to program the rate of insulin delivery and to modify the delivery rate according to the patient's expected or actual carbohydrate intake.
Recent changes in disposable battery design have resulted in battery voltage curves that remain substantially constant throughout the life of the battery. While the voltage of older types of disposable battery chemistry enables voltages to decrease gradually with use, new disposable batteries remain consistent throughout the battery's life until a short drop-off in voltage occurs. While this may prove to be harmless for certain products, it can be devastating to a portable insulin pump user. Portable insulin pump users rely on the infusion of insulin at preprogrammed times. A low battery condition may lead to an incorrect dosage or even lead to a missed dosage, resulting in an insulin pump that stops operating without warning. The results can obviously be devastating to the user.
International Standards IEC 60601-2-24 and 60601-1-8 govern the general requirements, tests and guidance for alarm system in medical electrical equipment, including infusion pumps and controllers. These standards require that infusion pumps include adequate alarm systems to notify the user when a low or critical battery condition is about to occur. However, it has recently become increasingly difficult to detect critical battery conditions with new disposable batteries in a timely matter due to the severe and sudden decline in voltage at the end of battery life. Because of the rapid decrease in voltage of disposable batteries onboard the insulin pump, there is currently no adequate means to detect a low or critical battery voltage condition.
Therefore, what is needed is an apparatus and method that can detect a low or critical battery condition in an infusion pump in a timely manner and can allow the user to continue to operate for a period of time after the primary disposable battery becomes depleted.